Drive-Cycle-Based Configuration Design and Energy Efficiency Analysis of Dual-Motor 4WD System With Two-Speed Transmission for Electric Vehicles

Abstract

The development of energy-saving technology is important to the promotion of electric vehicles. In the design process of electric vehicles, the drive configuration is generally determined first, and then the energy management strategy is studied. However, this process doesn’t design the drive configuration with higher energy saving potential from the economic perspective of vehicle driving conditions, but directly determines the drive configuration. So, in this paper, the characteristics of the vehicle’s driving conditions are analyzed firstly, and then based on the analysis results, a new dual-motor 4WD EV configuration with higher energy saving potential is proposed, which only has a two-speed transmission in the rear axle. Then the parameters of the proposed driving configuration are calculated to meet the vehicle dynamic or economic needs of various driving conditions. Then an energy management strategy is developed for the judgement of optimal torque distribution of the front and rear axle motors and gear shifting logic. Finally, the comparison simulations are conducted and the results show that, in WLTC, DM-2ST can reduce vehicle energy consumption by 9.13% and 4.84% respectively compared to DM-FTD and DM-OTD. In UDDS, DM-2ST can reduce vehicle energy consumption by 11.04% and 5.77% respectively compared to DM-FTD and DM-OTD.